std::experimental::ranges::Constructible

 

C++

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Technical Specifications

 

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Core language concepts
Same DerivedFrom ConvertibleTo	CommonReference Common	Integral SignedIntegral UnsignedIntegral	Assignable Swappable
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Destructible Constructible DefaultConstructible	MoveConstructible CopyConstructible	Movable Copyable	Semiregular Regular
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Defined in header <experimental/ranges/concepts>
template < class T, class... Args > concept bool __ConstructibleObject =  /* exposition only */     ranges::Destructible<T>() && requires(Args&&... args) {        T{ std::forward<Args>(args)... };        new T{ std::forward<Args>(args)... };     }; template < class T, class... Args > concept bool __BindableReference = /* exposition only */     std::is_reference<T>::value && requires(Args&&... args) {        T( std::forward<Args>(args)... );     }; template < class T, class... Args > concept bool Constructible() {     return __ConstructibleObject<T, Args...> || __BindableReference<T, Args...>; }		(ranges TS)

The concept Constructible<T, Args..>() is used to constrain a type to be either an object type constructible from a set of types, or a reference type that can be bound to those arguments.

Notes

As of the current working draft, Constructible<int&, char&>() is satisfied because the cast in __BindableReference is a reinterpret_cast.

Unlike std::is_constructible, Constructible requires a new-expression to be valid and also uses list-initialization, where narrowing conversions are not allowed, initializer-list constructors are preferentially called, and aggregate initialization can be performed. For example:

• Constructible<int, double>() is not satisfied, even though ConvertibleTo<double, int>() is satisfied and std::is_constructible<int, double>::value is true.
• Given struct A { int a; };, Constructible<A, int>() is satisfied, even though std::is_constructible<A, int>::value is false.

See also

is_constructibleis_trivially_constructibleis_nothrow_constructible (C++11)(C++11)(C++11)

checks if a type has a constructor for specific arguments (class template)